FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1913
1913 - 0330.PDF
pjam thistle down and the lightest feathers, with the bird soar ing 25 ft. overhead, and to my rarprixe these hmcuori al ways fell to the ground. Not satisfied with this, I flew up a kite with a ba^ of feathers attached in such a way that a jerk on the kite string would liberate a crowd of them. Sometimes one of these would bq caught in a rising wave of air which would elevate it several feet, but after travelling a short distance it would encounter a downward wave that would lower it again, and in time they seemed always to come to earth. These experi ments, of course, do not prove that rising air-currents do not exist. They do prove, however, that soaring flights can be accomplished when no rising air currents exist of sufficient velocity '11 support a feather. It is certainly hard to draw any conclusions from watching the per formances of soar ing birds. They seem to do things that upset all theories. I have seen them sailing when the smoke from a near-by chimney had an up ward trend, then remain aloft just as easily when the smoke from the same chimney blew out straight or had e re a a slightly downward motion. Three factors, however, seem to facilitate soaring, namely, sun, wind, and heat. On days that combine these three conditions, soaring seems to be MARCH 22, 1913. "Nature's Aeroplanes," by E. F. Andrews. at its best. If the weather is sufficiently favourable birds that under ordinary circumstances are flapping flyers can soar very readily. nave often seen whole flocks of common crows soar upward condor"" Wi"g aS '*" sudden,y endowed »><>> the power of the Personally I think that the phenomena of soaring flight is due to the fact that soaring birds have large supporting surfaces com- in.uively light weight and very low head resistance, in con sequence of which their gliding angle is very flat. This makes it possible for them to derive sufficient power for sustentation fTom very slight rising air currents, from air waves, and from the constant fluctuation of wind velocity, which their perfect mechanism and great skill enables them to take advantage of. Still, at times one 336 sees performances by these masters of air which, by any of the known laws, are certainly hard to explain. Pelican... Buzzard Osprev... Gull ... Duck* ... Hawk ... * Note the comparatively great weight carried by the duck, which is strictly a flapping flyer and a very poor glider. Area. Sq. ft. 4"66 474 3 I •S2 I'10 Sp Ft. 6 6 5 3 2 2 an. Ins. 8 O I 3 4 11 Cord. Ins. 11 T3 10 5 4i 7* Weight Lbs. 7'25 4 3'25 75 i-5 I"I25
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
